Not trying to make a spoiler, but the idea of the novel / movie was about how a modern slavery will look like. Is simply by consent, drugs, manipulation, deceive, lies. The drug addicts became the modern slaves of the ... you will see in the movie.
Also it contain some quite funny and dark humor scenes, sometimes you even think that is a bullshit movie with unnecessary long meaningless talks. But is not.
Is really interesting how they make this movie with real actors but animated.